The present disclosure relates to a cylindrically-shaped element for a vascular stent deployed in a vessel in a living body, such as a blood vessel, trachea or biliary duct, to scaffold the inner lumen of the vessel from inside, ensuring a flow channel in the vessel.
Heretofore, when stenosis occurs in a vessel of a living body such as a blood vessel including an artery, percutaneous transluminal angioplasty (PTA) is performed in which the stenosed portion in the vessel is expanded to improve the blood flow by inserting a balloon provided in the vicinity of the end of a balloon catheter and then inflating the balloon which is contracted initially.
Meanwhile, it is known that despite PTA applied initially, stenosis tends to recur at a high probability in the once stenosed site.
The current practice for prevention of such restenosis is to implant a cylindrical stent in the site treated with PTA. The stent is intended to scaffold a blood vessel from inside for the purpose of prevention of restenosis therein by being inserted into the blood vessel with its contracted state and subsequently expanded to be implanted therein.
As such a sort of stent, a stent comprised of a cylindrical metal member with slits to permit its expansion or contraction in diameter has been currently known.
Meanwhile, use of metal stents may lead to foreign-body reaction due to its long term presence in a living body, it is therefore not appropriate to leave them therein semi-permanently. Moreover, removal of metal stents after its deployment in a living body if needed, requires surgical procedures that impose severe burden on the patient.
To solve such inherent problems with metal stents, the present inventor has proposed a stent made of a biodegradable polymer in International Patent Publication Nos. WO92/15342 (Patent Document 1) and WO00/13737 (Patent Document 2).
A stent made of a biodegradable polymer has also been proposed in JP Laid-Open Patent Publication Nos. H-11-57018 (Patent Document 3) and 2004-33579 (Patent Document 4).
Furthermore, a vascular stent wherein several strands bent in zigzag are connected together to form a tubular body is disclosed in WO99/44535 (Patent Document 5).